The overall goal of this research program is to reveal developmental processes in primate retina that shape its complex topography. Previous results have provided the first detailed description of foveal development in humans and monkeys. In the present application, it is proposed to investigate the developmental mechanisms of photoreceptors, amacrine and bipolar neurons using both in vivo descriptive and in vitro experimental approaches. Aim 1 is to complete studies of the spatial and temporal sequence of cone and rod opsin mRNA/protein appearance and identify endogenous or exogenous factors that change the ratio or numbers of cone subtypes and rods. Aim 2 is to complete studies to determine the temporal and spatial patterns of synapse formation related to cellular birthdates. Aim 3 is to identify molecules which specify foveal address, support the maintenance or destruction of cell populations in the fovea or lead to the exclusion of other cell populations.